ASB - the country's second largest KiwiSaver provider - says nearly one in four of its members are not contributing to their retirement savings.
The bank, which has 400,000 out of the total 2.2 million people signed up to KiwiSaver, has launched a promotional campaign to encourage its members to start saving.
Blair Turnbull, ASB's general manager of wealth and insurance, said analysis of its members had shown the lack of contributions was strongly linked to having no regular salary.
Of its 400,000 members 34 per cent did not have a regular salary and of those four in five people did not contribute to their scheme at all. The unsalaried figures do not include under 18 year olds.
"That translates into more than 98,000 unsalaried ASB members not contributing."